If SO is still persisting in the hotel room fiction to save face with the children and/or others, that is his thing and probably not a bad thing. If he does return, there will be fewer things to explain to people outside the R.
But, if he is still using the hotel room fiction in his own head to mask the truth of his own actions — abandoning you, the kids, and the old R — I'm not sure how helpful that is to him. Again, though, that is his thing.
I would resist any temptation to buy into the fiction yourself. You live in a house that *was* a shared residence for the couple that was NM and SO. That relationship is gone. A new R between NM and SO may come that is a romantic partnership. But, right now, there is no "us" between NM and SO that would make having a shared residence appropriate.
Imagine the coworker you don't want to be friends with buying a *pair* of season tickets to the theatre just in case you change your mind...
